Combinatorial chemistry refers to techniques to collect, test, and store the resulting data for a material library containing tens, hundreds or even thousands of different materials or compounds. Combinatorial investigations require rapid screening techniques to test and evaluate variations of composition, structure and property within a material library. Screening may be done by different techniques. X-ray diffraction is one suitable screening technique, because abundant information on the atomic arrangement of the sample can be revealed from the diffraction pattern. A different screening technique is Raman spectroscopy, which may be used to measure the characteristic vibration frequencies determined by the chemical composition and chemical bond. Whichever screening technique is used, the combinatorial analysis involves sampling a number of different samples typically arranged adjacent to each other on a sample holder. Sample data is collected for all the samples in the sample array, and used collectively as part of the analysis.